1. Field of the Invention
The present invention relates to an alarm system for warning the driver of a vehicle when his vehicle is dangerously close to tipping over because his vehicle is positioned on too steep an incline.
2. Description of the Prior Art
Vehicles such as earthmoving equipment, including bulldozers, backhoes, and graders, and agricultural machinery, including harvesters, tractors, and lawn mowers, are frequently required to operate on steeply inclined surfaces such as hillsides and embankments. It is very difficult for a vehicle operator to determine visually if an incline is steep enough to cause his vehicle to roll over when the vehicle is travelling transversely to the downhill direction. To warn the vehicle operator that his vehicle is on too steep a slope and dangerously close to rolling over, many warning systems have been proposed in the prior art.
U.S. Pat. No. 3,804,435, issued to See et al., shows a vehicle roll-over safety system which includes inflatable bags that protect the vehicle operator as the vehicle rolls over. The inflatable bags are activated by a mercury switch that is responsive to the tilting of the vehicle.
U.S. Pat. No. 3,846,781, issued to Smith, shows a pendulum slope indicator that indicates to the vehicle operator the angle at which his vehicle is tilted relative to the horizontal. Also, when the vehicle is tilted laterally at an extreme angle, the pendulum makes an electrical contact to turn on a warning light. The Smith system has the drawback that the angle at which the warning light is turned on cannot be adjusted. Therefore the slope indicator of Smith cannot be transferred to another vehicle whose center of gravity is at a different height above the plane defined by the vehicles wheels or tracks, than the one for which the slope indicator was designed. Further there is no provision for a steady tip-over alarm which would generate a very loud, continuous noise to attract the attention of other people in the area in the event the vehicle rolls over.
U.S. Pat. No. 3,848,750, issued to Hoge, shows a crane tip alarm wherein a pendulum carrying a light source is positioned directly above a light detector. Relative movement of the pendulum interrupts the shining of the light beam onto the detector, thus causing an alarm. In addition, a conductor attached to the pendulum can make contact with an annular conductor surrounding the pendulum to also cause an alarm. The Hoge device causes an alarm even with the slightest deviation of the crane platform from the horizontal, and its sensitivity is not adjustable in contrast to the present device. Further there is no provision for a steady tip-over alarm which would generate a very loud, continuous noise to attract the attention of other people in the area in the event the vehicle rolls over.
U.S. Pat. No. 4,016,535, issued to Dinlocker, shows a tilt alarm wherein an alteration in the magnetic field surrounding a reed switch, caused by relative movement of a pendulum composed of a permanent magnet, precipitates the opening of the reed switch which in turn activates an alarm. The Dinlocker device requires a bleed current to flow through the reed switch under normal conditions, thus leading to an undesirable drain on the power supply. In addition, the angle at which the Dinlocker device generates an alarm is not adjustable in contrast to the present invention.
U.S. Pat. No. 4,145,682, issued to Cook, shows a tilt alarm using two mercury switches. The Cook system suffers from the drawback that it requires the use of a hazardous material namely mercury.
U.S. Pat. No. 4,700,479, issued to Saito et al., shows a tilt alarm having a magnetically damped pendulum. The pendulum has a reflective pattern on its surface which is illuminated by a light source. A photo-sensor receives the light reflected by the reflective pattern, and an alarm is generated when the light radiation to the photo-sensor is interrupted by relative movement of the pendulum. The Saito et al. device suffers the drawback that the angle at which the device generates an alarm is not adjustable in contrast to the present invention.
U.S. Pat. No. 4,952,908, issued to Sanner, shows a trailer stability monitor using two mercury switches. The Sanner system suffers from the drawback that it requires the use of a hazardous material namely mercury.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.